Power hydraulic cylinder

ABSTRACT

A power hydraulic cylinder for fastening workpieces to be machined in which a piston and a rod of the cylinder are mounted so as to be capable of displacing relative to each other. The cylinder is provided with an accumulating spring which is acted upon by the piston and the rod under the action of the working liquid pressure, and which, while being deformed, provides for preservation of a constant clamping force and autonomous operation of the cylinder when the latter is disconnected from the pipe line supplying the high pressure working liquid.

ite States Paten Shiilevich [45] Apr. 11, 1972 [54] POWER HYDRAULIC CYLINDER 3,394,631 7/1968 Thompson ..92/165 x [72] Inventor: Izrail Yakovlevich Shimilevich, ulitsa FOREIGN PATENTS OR ppu Chernyshevskogo, 3/7 kv. 43, Moscow, U R 584,683 1958 Italy ..269/25 [22] Filed: 1970 Primary ExaminerEdgar W. Geoghegan 21 A l. N 19,845 Assistant Examiner-Leslie J. Payne 1 pp Attorney-Waters, Roditi, Schwartz& Nissen [52] U.S.Cl ..92/24,92/1 17, 92/163 [57] ABSTRACT [51] Int.Cl ..Fl5b /26 158 Field 6: Search ..92/163, 130,60, 165, 117, A W" llydraullc i fastenmg be 92/66 28 27 267/25 machmed in which a p1ston and a rod of the cylinder are mounted so as to be capable of displacing relative to each other. The cylinder is provided with an accumulating spring [56] References Cited which is acted upon by the piston and the rod under the action UNITED STATES PATENTS of the working liquid pressure, and which, while being deformed, provides for preservation of a constant clamping 2,955,578 10/1960 Flessate et al ..92/163 X force and autonomous operation f the cylinder when the 219551618 10/1960 Muer "(H/163 X latter is disconnected from the pipe line supplying the high 2,988,058 6/1961 Warnecke ..92/ pressure workingliquid 3,176,590 4/1965 Uhtenwoldt et a1. .....92/28 X 3,203,319 8/1965 Cook ..92/1 17 X 3 Claims, 6 Drawing Figures A5 ii!" r .Nw Z a a 6 11.2 1%

Ql ll.

PATENTEDAPR I 1 I972 SHEET 2 BF 5 F/G Z POWER HYDRAULIC CYLINDER The present invention relates to power hydraulic cylinders used preferably in clamping devices to fasten workpieces to be machined.

Employment of hydraulic clamping devices makes it possi ble to mechanize the process of fastening workpieces to be machined in metal-cutting machines under the modern conditions of high-speed and power cutting. The reduction of auxiliary time, provided by the mechanization of these operations, attributes to a considerable extent to the labor efficiency during the mechanical treatment of workpieces and excludes the factor of fatiguability of the worker.

Hydraulic clamping devices, as compared to pneumatic, pneumatic hydraulic and mechanical hydraulic ones, are more reliable in operation and economical. They allow working under high pressures when many clamping points are used simultaneously, thus providing for a high reliability of the clamping by means of a constant pressure in the main line.

Known in the art is a single action power hydraulic cylinder used in clamping devices and comprising a body which accomodates a piston, an operating rod and a cuperator spring mounted therein, and is equipped with a pipe connection havin g a non-return valve to supply the working liquid.

It is an object of the present invention to provide a power hydraulic cylinder for a clamping device which will permit fastening of workpieces to be machined without constant connection with the hose supplying the working liquid.

Another object of the present invention is to reduce the cost of the mechanical treatment of workpieces.

Still another object of the present invention is to increase the labor efiiciency.

A further object of the present invention is to obtain reliability of the fastening of the workpieces to be treated due to the development of a constant clamping force.

Other objects and advantages will be shown hereinbelow with reference to an exemplarily embodiment of the inventron.

Therein, in a single-action power hydraulic cylinder used in clamping devices and comprising a body having a piston, a rod and a recuperator spring mounted therein, and equipped with a pipe connection having a non-return valve to supply the working liquid, in accordance with the present invention, the piston and the rod are mounted so that they are capable of displacing relative to each other, and the cylinder is equipped with an accumulating spring which is acted upon by the piston and the rod in the course of displacement thereof in the cylinder under the action of the pressure of the working liquid, and which, while being deformed, provides for preservation of a constant clamping force and autonomous operation of the cylinder after the latter is disconnected from the hose supplying the pressurized working liquid.

The accumulating spring may be disposed between the piston and the rod, and used as an intermediate part for maintaining a constant value of the hydraulic clamping force.

It is possible to dispose the accumulating spring between the cylinder bottom and the rod, and to build up a clamping force directly by means of the spring after the piston is relieved of the pressure of the working liquid.

As a result of the present invention there has been provided a power hydraulic cylinder which in the course of operation is not constantly connected to a hose used for supplying the working liquid, and, therefore, may be used in metal-cutting machines employing rotating clamping devices, as well as in machines in which the table moves along a great distance.

In the power hydraulic cylinder built in accordance with the present invention, the hoses used for supplying the working liquid are but temporarily connected thereto by a quickoperating detachable coupling tip to inject a high-pressure working liquid into the space of the hydraulic cylinder, and they are disconnected before the machine operation is started. With the supply hoses disconnected, the power cylinders operate autonomously, employing movable clamping means and preserving a constant clamping force built up on the accumulating spring as a result of the working liquid pressure.

Such autonomous operation of the power hydraulic cylinders, carried out with the supply hoses disconnected therefrom and ensuring maintenance of a constant clamping force in the course of operation, is provided by an accumulating spring built-in the cylinder, the rigidity of said spring corresponding to the hydraulic force of the piston.

The disposition of the accumulating spring in the cylinder relative to the operating members of the latter detennine the designation of the hydraulic pressure with regards to the spring.

With the accumulating spring disposed between the piston and rod, the power hydraulic cylinder provides, in its operating position, a clamping force, whereas the accumulating spring maintains the working liquid pressure.

In case the accumulating spring is disposed between the rod and the cylinder body, the power hydraulic cylinder provides, in its operating position, a clamping force acting upon the operating rod by the force of rigidity of the compressed accumulating spring after the pressure of the working liquid is reduced (the working liquid is drained off).

Each of the afore-said cylinders may be made in such a way, that the clamping force may be directed toward or from the table fastening a workpiece.

The following description of exemplary embodiments of the present invention is given with reference to the accompanying drawings, in which:

FIG. 1 shows a longitudinal section of a power hydraulic cylinder, according to the present invention, in which the accumulating spring is disposed between the piston and the operating rod, and the hydraulic force is directed towards the table fastening a workpiece;

FIG. 2 shows a longitudinal section of a power hydraulic cylinder, according to the present invention, in which the accumulating spring is disposed between the piston and the operating rod, and the hydraulic force is directed from the table fastening a workpiece;

FIG. 3 shows a longitudinal section of a power hydraulic cylinder, according to the present invention, in which the accumulating spring is disposed between the cylinder bottom and the operating rod, and the clamping force, provided by a spring, is directed for the table fastening a workpiece;

FIG. 4 shows a longitudinal section of a power hydraulic cylinder, according to the present invention, in which the accumulating spring is disposed between the cylinder bottom and the operating rod, and the clamping force, provided by a spring, is directed towards the table fastening a workpiece,

FIG. 5 shows a power hydraulic cylinder, shown in FIG. 2, in operation, built in a clamping device; and

FIG. 6 shows the power hydraulic cylinder in FlG.4,clamping a part independently without a clamping device.

In a power hydraulic cylinder shown in FIG. 1 a body I having a barrel 2 and a head 3 welded to each other is equipped with packings 4 and is coupled during the running fit with a piston 5 which, in its turn, is coupled with a rod 6 screwed into a slide block 7 of a table 8 of a machine not shown in the drawing), either directly, or through the intermediary of a threaded sleeve 9 used to increase the length thereof with the aid of a bolt 10 when high workpieces to be machined are to be fastened. Thus, the rod 6 is used to freely secure the cylinder together with workpieces 11 to be machined to the table of the machine by manually turning the rod by means of a screw driver engaged in a groove 12.

Disposed between the rod 6 and the piston 5 is an accumulating disk spring 13.

To supply the working liquid into the cylinder, the body 1 is provided with a pipe connection 14 having a non-retum valve (not shown in the drawing) of a conventional design built therein.

Mounted between the rod 6 and the cylinder bottom 15 is a recuperator spring 16.

With the working liquid being supplied through the pipe connection 14 into a working space 17 of the cylinder, the piston 5 together with the rod 6 and the accumulating spring 13 is raised to compress the recuperator spring 16, whereas the cylinder body 1 is lowered and simultaneously eliminates all the clearances to be found in the contact location of the clamping members. With the recuperator spring 16 partially compressed and all the clearances in the clamping members eliminated, the piston 5 during its further movement under the action of the working liquid pressure will compress the accumulating spring 13 up to a limit value h of its deformation, corresponding to the final maximal clamping force of the hydraulic cylinder. By this force the cylinder body 1 presses the workpieces 11 against the table 8 by means of a clamp 18.

If, in accordance with the technical requirements, the workpiece is too high and hydraulic cylinder does not protrude beyond the workpieces being machined, the latter are secured by means of a clamp 19 embracing the cylinder body 1 and secured by means of a nut 20 on the outer threading 21 of the hydraulic cylinder body 1, as is shown by a dotted line for clamping a workpiece 22.

After the workpiece 11 or 22 is clamped, the hose (notshown in the drawing) supplying the working liquid is automatically disconnected, whereby the non-return valve disposed in the pipe connection is automatically closed, and the compressed accumulating spring 13 by acting upon the piston 5 maintains a constant hydraulic pressure of the working liquid in the cylinder space 17, acting upon the cylinder body 1, and thus providing for a maximal clamping force.

To eliminate the clamping force, the working liquid is drained from the hydraulic cylinder space 17 into the hose which is connected thereto again, the recuperator spring 16 raises the hydraulic cylinder body 1, and the released accumulating spring 13 is returned into its initial position.

FIG. 2 shows a power hydraulic cylinder of the same type as the cylinder shown in FIG. 1, but using a pushing force for clamping. A body 23 consisting of two parts a head 24 and a barrel 25 welded to each other, is coupled with a piston 26 via a packing 27 and rests upon an accumulating disc spring 28 which at its lower end portion rests upon a rod 29. The rod 29, in turn, rests upon a recuperator spring 30 resting at its lower end portion upon the cylinder bottom 31. The rod 29 together with a base 32 screwed thereto is coupled during the running fit with the bottom 31, which makes it possible for the body 23 to move upward within the limits of the clearance b to be found between the bottom 31 and the rod 29 thus deforming the spring 30.

Screwed into the body 23 is a pipe connection 33 having a non-return valve 33a therein.

To clamp high parts 34, use is made of a clamp 35 with a bolt 36 whose length may be enlarged with the aid of a threaded sleeve 37 the lower end of which is to be fixed in a slot of a table 38 through the intermediary of a slide block 39. The clamp 35 and the bolt 36 are loosely secured by means of a nut 40 on a spherical washer 41 by hand when mounting the hydraulic cylinder.

To clamp low parts 42, use is made of a clamp 43 whose position is fixed by means of a nut 44 screwed onto an outer threading 45 of the cylinder 23. The clamp 43 clamps the workpiece 42 by a pulling force developed by the hydraulic cylinder through a spherical washer 46 of a bolt 47 with a nut 48.

A workpiece is clamped in the following way:

The working liquid supplied under pressure via the pipe connection 33 into the space 49 of the cylinder lowers the piston 26 and simultaneously raises the body 23 of the cylinder, thus eliminating clearances in the clamping members. With the clearances eliminated, the movement of the body 23 of the cylinder is discontinued, whereas the piston, while continuing to move downward, deforms the accumulating spring 28 up to its limit value b of deformation, corresponding to the maximal force of clamping. The working liquid contained in the space 49 simultaneously exerts pressure upon the cylinder body 23 too, thereby acting upon the clamp 35 or 43 with a maximal force of clamping. Then, the supply hose together with the quick-operating tip (not shown in the drawing) is disconnected from the pipe connection 33,

and the non-return valve 33a therein automatically operates, whereas the clamping force acting upon the clamp 35 or 43 and, hence, upon the workpiece 34 or 42 remains, as due to the accumulating spring 28, the pressure of the working liquid in the space 49 remains constant.

To release the workpiece 34 or 42 after it has been machined, the hose is connected to the pipe connection 33 to drop the pressure and drain the working liquid into the hydraulic main.

The power hydraulic cylindershown in FIG. 3 has a body 50 consisting of two parts a head 51 and a barrel 52 welded to each other; it is equipped with packings 53 and is coupled with a piston 54 with a running fit. In the course of travel, the piston 54 is coupled with an operating rod 55 without employing any packing. An accumulating disk spring 56 is disposed between the rod 55 and the cylinder bottom 57, and rests thereon by one side from below and the shoulder of the rod 55 by its other side from above. A recuperator spring 58 rests by one end portion also on the rod 55, and by its other end portion on the piston 54.

To supply the working liquid, the body 50 is provided with a pipe connection 59 having a non-return valve 59a therein.

With the working liquid being supplied via a pipe connection 59 into a working space 60 of the cylinder, the piston 54, as well as the rod 55, are lowered to deform both the accumulating spring 56 and recuperator spring 58. The accumulating spring 56 is compressed up to its limit value of deformation equalling the distance between the lower end portion of the rod 55 and the bottom 57.

With the afore-mentioned parts occupying this position, a clamp 61 is brought to the operating rod 55 of the hydraulic cylinder and is fixed thereon, the other end portion of said clamp 61 resting upon the workpiece 62 to be clamped. The clamp 61 is fixed by means of a nut 63 of a slot bolt 64 by hand to eliminate clearances in the clamping members.

Thereupon, the pressure in the working space 60 is dropped by draining-off the working liquid, as a result of which the piston 54 under the action of the recuperator spring 58 is raised into its initial position, and the accumulating spring 56, while being compressed, acts upon the operating rod 55 and via the latter upon the clamp 61, thereby providing for a maximal force of clamping corresponding to the value of its deformatron.

Then the hose is disconnected and with the hydraulic pressure in the space 60 dropped, the cylinder operates autonomously, thus providing for clamping the workpiece 62 being machined by means of a spring.

In order to remove the workpiece 62 after the machine is stopped, the hose is connected to the pipe connection 59 of the cylinder, the working liquid being supplied into the cylinder via said pipe connection, and the piston 54 is lowered under the action of the pressure of the working liquid to complete the compression of the accumulating spring 56, whereupon the workpiece 62 is removed.

The high-pressure working liquid is used in such power cylinders in order to compress the accumulating spring only.

FIG. 4 shows a power hydraulic cylinder of the same type as the cylinder shown in FIG.3, but employing a force of clamping directed towards the table fastening a workpiece.

The cylinder body 65 welded of two parts a head 66 of the cylinder and a barrel 67 is coupled during the running fit with a piston 68 by means of a packing 69.

The piston 68 rests upon a recuperator spring 70 which has a stationary rod 71 secured in a table 72 of the machine through the intermediary of a slide block 73.

Mounted between the rod 71 and the cylinder bottom 74 is a disc spring 75 which is deformed under the action of displacement of the cylinder body 65 along the rod 71 coupled with the bottom 74 up to the stop, as shown in drawing, wherein the hydraulic cylinder is in its operation clamping position when its disk spring 75 is compressed up to its limit deformation.

Workpieces 76 are clamped in the following way:

A high-pressure working liquid is supplied into the cylinder space 78 via a hose connected thereto from the hydraulic main via the pipe connection 77. Under the action of the pressure of the working liquid the piston 68 is lowered to deform the recuperator spring 70 and thrust against the stationary rod 71 at the top. whereupon the cylinder body 65 begins to move upward deforming the disc spring 75 until it thrusts against the rod 71 at the bottom. In this position, the workpiece 76 is clamped by hand by a clamp 79 with the aid of a nut 80 on an outer threading 81 of the cylinder body 65.

Thereupon, the working liquid is drained from the space 78 via the pipe connection 77 into the main, the piston 68 is brought back to its initial position under the action of the recuperator spring 70, and the deformed disc spring 75 acts with a maximal force upon the cylinder body 65, thus clamping the workpiece 76 through the intermediary of the clamp 79.

To release the workpiece 76, a supply hose is connected to the pipe connection 77, and the disk spring 75 is compressed again to release the clamp 79, whereupon the workpiece is removed from the machine.

To clamp high parts, as shown in the drawing, use is made of either a bolt 82 for parts 83 whose length may be enlarged by means of a threaded sleeve 84 and which may be screwed in a thread 85 of cylinder body 65 with its clamp 86, nut 87 and spherical washer 88 or a bolt 89 for parts 90 which is screwed in a slide block 91 of the table 72 and fix parts 90 by means of clamp 92 and nut 93 providing spring clamping after draining the working liquid.

FIG. 5 shows a clamping device with a hydraulic cylinder shown in FIG.2, in which the bolt 47 with the nut 48 and the spherical washer 46 is screwed in a clamping device 94 fixed on the table of a machine (not shown). The cylinder body 23 is provided with the clamp 43 and the nut 44 for clamping the parts 42. The working liquid is supplied through the pipe connection 33.

FIG. 6 shows the hydraulic power cylinder shown in FIG. 4

in operation providing clamping of the parts without a device. To fix it use is made of the rod 71 screwed through the slide block into the table 72 of a machine. Clamping of the parts 76 is carried out by means of the clamp 79 with the nut screwed on the thread 81 of the cylinder body 65.

The working liquid is supplied through the pipe connection 77 by means of a hose of a hydraulic main (not shown).

What is claimed is:

l. A singleaction power hydraulic cylinder comprising a hollow body with a slidable piston therein, a rod and a recuperator spring mounted within said body, said piston and rod being separate and mounted so as to be displaceable relative to each other; a pipe connection adapted for connection with a supply of pressurized working liquid and including a nonretum valve, said pipe connection being attached to periodically supply the working liquid into said cylinder from the supply; an accumulating spring in said body around said rod and acted upon by said piston and rod under the action of the pressure of the working liquid so as to be deformed to a predetermined position, and means to fix said piston and rod for common displacement in said hollow body after said accumulating spring has been deformed to said pre-determined position for maintaining a constant clamping force and autonomous operation of the cylinder after the latter is disconnected from the supply of pressurized working liquid and the non-retum valve has closed.

2. A power hydraulic cylinder as claimed in claim 1, in which said accumulating spring is disposed between said piston and rod and maintains a constant value of hydraulic pressure in the hollow body.

3. A power hydraulic cylinder as claimed in claim 1, in which said accumulating spring is disposed between said cylinder and said rod to provide a clamping force acting directly on the rod after the piston is relieved of the pressure of the working liquid. 

1. A single-action power hydraulic cylinder comprising a hollow body with a slidable piston therein, a rod and a recuperator spring mounted within said body, said piston and rod being separate and mounted so as to be displaceable relative to each other; a pipe connection adapted for connection with a supply of pressurized working liquid and including a non-return valve, said pipe connection being attached to periodically supply the working liquid into said cylinder from the supply; an accumulating spring in said body around said rod and acted upon by said piston and rod under the action of the pressure of the working liquid so as to be deformed to a pre-determined position, and means to fix said piston and rod for common displacement in said hollow body after said accumulating spring has been deformed to said predetermined position for maintaining a constant clamping force and autonomous operation of the cylinder after the latter is disconnected from the supply of pressurized working liquid and the non-return valve has closed.
 2. A power hydraulic cylinder as claimed in claim 1, in which said accumulating spring is disposed between said piston and rod and maintains a constant value of hydraulic pressure in the hollow body.
 3. A power hydraulic cylinder as claimed in claim 1, in which said accumulating spring is disposed between said cylinder and said rod to provide a clamping force acting directly on the rod after the piston is relieved of the pressure of the working liquid. 